Blacklist Check
Is this IP address flagged?
Check any IPv4 address against major DNS blackhole lists (DNSBLs) used by email servers and security tools to block spam and abuse.
What is a DNS Blacklist (DNSBL)?
A DNSBL (DNS-based Blackhole List), also called an email blacklist or IP blocklist, is a database of IP addresses that have been reported for sending spam, hosting malware, or other abusive activity. Email servers and security tools query these lists in real time to decide whether to accept or reject incoming connections.
If your IP address is listed, your outgoing emails may be silently dropped, bounced, or sent to spam folders — even if you've done nothing wrong. This can happen if your ISP has reassigned a previously-abused IP to your connection, or if your network has been compromised by malware sending spam without your knowledge.
Email deliverability
Being listed on a major DNSBL like Spamhaus ZEN can cause your emails to be rejected by Gmail, Outlook, and most corporate mail servers.
Spamhaus ZEN
The most widely used DNSBL. ZEN combines multiple Spamhaus lists covering spam sources, hijacked networks, and known spam operations.
SpamCop
SpamCop lists IPs reported by users as spam sources. Listings expire quickly — usually within 24 hours if spam stops.
How to delist
If your IP is listed, contact the blacklist operator directly. Most offer a self-service delisting portal once the spam issue is resolved.